EDIT: I found the solution to my problem while writing the post. I'm leaving the description below in case it helps anyone else.

SOLUTION: The Kindle Fire HD doesn't seem to support books in subfolders of the "Books" folder on the device. Put the .mobi files in the root of /Books.

I've got Calibre 0.8.69. I have enabled the beta drivers and am able to send books to the Fire HD via MTP.

I've confirmed the .mobi files are in the "Books" folder on the Fire HD. They are in subfolders with the authors name.

However, the books don't show up on the Fire HD anywhere. I've looked in books and docs and I have rebooted the device several times.

I have successfully sent the books to the Fire HD using the @kindle.com email address. Those show up in the doc section on the Fire HD. Interestingly these appear to show up on the HD in the root of the "Books" folder with names like B003SX0XY4_EBOK.prc and B004MME2OC_EBOK.prc.

Yeah just customize the driver and untick epub for the list of formats to send to the device. In the next release, calibre will detect the device as a Fire and default to sending only amazon formats into the documents or books folder on the Fire with no subdirectories.

You can configure calibre to not create subfolders, change the template to

{title} - {authors}

by right clicking the device in calibre and choosing configure this device.

This doesn't help on my new 2nd Gen Fire ($159) as they still don't appear with the other books (or any other place I look). They only show up when they are in no sub-directory but are directly in the Books folder.

This doesn't help on my new 2nd Gen Fire ($159) as they still don't appear with the other books (or any other place I look). They only show up when they are in no sub-directory but are directly in the Books folder.

I have the same problem with the sub directory’s, so don't use Calibre to transfer books now, it's just as easy to drag an drop directly in to "Books" directory, even then some only show in Documents, don't understand this at all as books are in the "Books" directory.

I have the same problem with the sub directory’s, so don't use Calibre to transfer books now, it's just as easy to drag an drop directly in to "Books" directory, even then some only show in Documents, don't understand this at all as books are in the "Books" directory.

I have spent hours trying to get it to work, with no luck.

In addition to setting the device to not create sub folders, make sure there's not a PDOC tag but instead an EBOK tag in the mobi. then set it to send to the /documents folder and it all works like a champ and shows in the Books bookshelf display.

I just purchased an Android powered tablet that had Kindle for Android already installed. The first book I tried to move to the tablet using Calibre didn't show as being downloaded to the Kindle reader. I checked the files and Calibre had moved an Epub file of the book to the Kindle folder on the tablet. I tried moving that Epub file to the other kindle ebook directory (android/data/com.amazon.kindle) but the reader still didn't find the file. I even tried turning thetablet completely off (powered down) and restarting it. Still no joy. After reading this post, I changed the device options to exclude Epub files, downloaded a book in Mobi format and the reader displays it with all the other Amazon books.

Thanks guys! Even though this isn't a Kindle Fire, your suggestions worked!!!

In addition to setting the device to not create sub folders, make sure there's not a PDOC tag but instead an EBOK tag in the mobi. then set it to send to the /documents folder and it all works like a champ and shows in the Books bookshelf display.

Thanks for the reply:

Can't play with kindle anymore, it's all wrapped up for the wife’s Christmas present all her books are loaded, kindle is all fully charged so it's all set for her to use as soon as she opens it on Christmas day. I will play with it a little more after Christmas the next time she needs a book loading on it.

This doesn't help on my new 2nd Gen Fire ($159) as they still don't appear with the other books (or any other place I look). They only show up when they are in no sub-directory but are directly in the Books folder.

Ok I am using the newest version on Calibre (just downloaded last night) and tried to change my epubs into mobi for my new Kindle Fire HD. No luck then i say your post and went beck in and dumped all the books in calibre and reimported some. I even used the mobi files I created last night and changed that one setting to EBOK. It gave me 2 mobi files when it was all done.

I placed the mobi file in the document folder on the cloud and still no luck. I even tried the original mobi (that's the second one Calibre created) and still no luck.

I am so lost. I have over 30 books in epub but can't get them on to my new Fire HD

I recently got a Kindle Fire HD after my Kindle Keyboard broke. I am back up and running now, so I went to transfer my Calibre library to it with no luck. Calibre is not able to detect my Kindle Fire HD. I have spent the past two days reading up on this problem and have tried every troubleshooting idea that I could find and my husband did as well...to no avail.

I tried emailing books to my kindle email address, but then learned that this doesn't work with the my Kindle type.

I read where with Windows XP users, the Kindle Fire HD is not recognized on the computer as a letter drive and I confirmed this is the case. Because of this, we can only transfer books wirelessly, for which I would need the Calibre Companion app. So I got the app, but only to find out that this app does not work with the Kindle Fire HD.

I checked to make sure I have Windows Media Player 11, which I do.

I read the thread back in mid-Sept that Kovid posted about this detection issue and the solution was to enable the beta version in Calibre, which I did using his directions for the plugin tweak. My device was still not recognized. Then I kept reading and saw that this solution was for the older version of Calibre and from what I understand, doesn't work with the newer version. I have installed and have been running version 0.9.13 throughout this process.

I am just totally lost and frustrated because I have all of these awesome books just sitting there waiting for me to read and I can't get them on my stinking Kindle! I never had a single issue putting them on my Kindle Keyboard. HELP PLEASE!